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In my area (Romania) vegetarianism is rather new and has a small number of proponents. While being a vegetarian, from time to time, I hear from some persons (including medical doctors) that one should necessarily eat meat because it has "higher quality proteins".

However, no one has really managed to explain me what that means.

I have searched a little bit and found this article which makes me feel that protein quality assessment is far from being trivial:

Protein quality describes characteristics of a protein in relation to its ability to achieve defined metabolic actions. Traditionally, this has been discussed solely in the context of a protein's ability to provide specific patterns of amino acids to satisfy the demands for synthesis of protein as measured by animal growth or, in humans, nitrogen balance. As understanding of protein's actions expands beyond its role in maintaining body protein mass, the concept of protein quality must expand to incorporate these newly emerging actions of protein into the protein quality concept. New research reveals increasingly complex roles for protein and amino acids in regulation of body composition and bone health, gastrointestinal function and bacterial flora, glucose homeostasis, cell signaling, and satiety. The evidence available to date suggests that quality is important not only at the minimum Recommended Dietary Allowance level but also at higher intakes.

Question:

Is it true that the proteins one gets from meat are superior to those coming from vegetarian sources?

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One difference between animal protein and plant protein is that plant protein breaks down much more quickly than animal protein (which is why that feeling of being horribly full for a long time after eating lots of animal protein doesn't usually happen with plant protein).

This is why some ultra athletes say they prefer plant protein when you need to eat as much as they do, they need the protein to break down quicker so that they can utilize it as soon as possible pre and post workouts.

Vegan Ultra-marathoner Scott Jurek is one proponent of plant based proteins for this reason (among other reasons). There are also a number of strength athletes who are vegan as well.

Team USA's only male weightlifter at the Rio Olympics - Kendrik Farris

Vegan Gains

So as your question stated, "protein quality" is a very complicated questions, but millions of people live healthy vegan and vegetarian lives and some people break world records on a vegan diet.

Some people worry about getting all of their amino acids from plant sources but it is perfectly possible to do so. (Source: Plant Foods Have a Complete Amino Acid Composition)

Also, here is a link to quotes by 10 major health organizations stating that a well planned vegan lifestyle is "healthful" and "nutritionally adequate" even for children and women who are pregnant/nursing.

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One aspect of "protein quality" refers to how close a type of protein is to being "complete", i.e. containing all the nine essential amino acids in sufficient amounts.

Most meat, fish, whey (milk protein) and eggs are complete protein sources.

As covered in other questions, there are many vegan complete protein sources as well, such as soy beans, lentils and rice, or maize and black beans. (Even potatoes are complete protein sources, but they contain little protein.)

An incomplete vegan protein source is wheat protein, found in bread, pasta and Seitan.

Have a look at these questions:

So, in summary, no, meat protein is not per se superior than vegan protein. However, one needs to take care not to rely on incomplete protein.

Sources: http://www.nap.edu/read/10490/chapter/12

  • 2
    Protein quality is also evaluated in terms of absorption rate. – Ramon Melo Feb 7 '17 at 17:52
  • @RamonMelo, good point, I didn't address that. Edited. I don't know any good sources on that, but LennonR's answer seems to cover that aspect a bit. – Turion Feb 7 '17 at 18:25

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